function launchPopup(divid) {
  var scrolledY;
  if( self.pageYOffset ) {
    scrolledY = self.pageYOffset;
  } else if( document.documentElement && document.documentElement.scrollTop ) {
    scrolledY = document.documentElement.scrollTop;
  } else if( document.body ) {
    scrolledY = document.body.scrollTop;
  }
  var top_pos = parseInt(document.getElementById(divid).style.top);
  if (scrolledY > top_pos) {
    var topOffset = (scrolledY + 20);
    document.getElementById(divid).style.top = topOffset + "px";
  }
  document.getElementById(divid).style.display = "block";
}
function checkform ( form )
{
  if (form.email.value.indexOf(' ')==-1 && 0<form.email.value.indexOf('@') && form.email.value.indexOf('@')+1 < form.email.value.length) {
    if (form.comments.value == "") {
      alert( "Please enter your comments." );
      form.comments.focus();
      return false ;
    }
    return true;
  } else {
    alert ('Please enter a valid email address.');
    form.email.focus();
    return false;
  }
}